Table of Contents

WireGuard client

This article relies on the following:

Introduction

Goals

  • Encrypt your internet connection to enforce security and privacy.
    • Prevent traffic leaks and spoofing on the client side.
  • Bypass regional restrictions using commercial providers.
    • Escape client side content filters and internet censorship.
  • Access your LAN services remotely without port forwarding.

Command-line instructions

1. Preparation

Install the required packages. Specify configuration parameters for VPN client. 

# Install packages
wireguard-tools
 
# Configuration parameters
VPN_IF="vpn"
VPN_SERV="SERVER_ADDRESS"
VPN_PORT="51820"
VPN_ADDR="192.168.9.2/24"
VPN_ADDR6="fd00:9::2/64"

2. Key management

Generate and exchange keys between server and client. 

# Generate keys
umask go=
wg genkey | tee wgserver.key | wg pubkey > wgserver.pub
wg genkey | tee wgclient.key | wg pubkey > wgclient.pub
wg genpsk > wgclient.psk
 
# Client private key
VPN_KEY="$(cat wgclient.key)"
 
# Pre-shared key
VPN_PSK="$(cat wgclient.psk)"
 
# Server public key
VPN_PUB="$(cat wgserver.pub)"

3. Firewall

Consider VPN network as public. Assign VPN interface to WAN zone to minimize firewall setup. 

# Configure firewall
uci rename firewall.@zone[0]="lan"
uci rename firewall.@zone[1]="wan"
uci del_list firewall.wan.network="${VPN_IF}"
uci add_list firewall.wan.network="${VPN_IF}"
uci commit firewall
service firewall restart

4. Network

Configure VPN interface and peers. Note that network addresses require a netmask or they will default to defining a subnet of /32, and fail to route to the other end of the tunnel! The Allowed IP field can be a /32 as it is describing IPs rather than a subnet. 

# Configure network
uci -q delete network.${VPN_IF}
uci set network.${VPN_IF}="interface"
uci set network.${VPN_IF}.proto="wireguard"
uci set network.${VPN_IF}.private_key="${VPN_KEY}"
uci add_list network.${VPN_IF}.addresses="${VPN_ADDR}"
uci add_list network.${VPN_IF}.addresses="${VPN_ADDR6}"
 
# Add VPN peers
uci -q delete network.wgserver
uci set network.wgserver="wireguard_${VPN_IF}"
uci set network.wgserver.public_key="${VPN_PUB}"
uci set network.wgserver.preshared_key="${VPN_PSK}"
uci set network.wgserver.endpoint_host="${VPN_SERV}"
uci set network.wgserver.endpoint_port="${VPN_PORT}"
uci set network.wgserver.persistent_keepalive="25"
uci set network.wgserver.route_allowed_ips="1"
uci add_list network.wgserver.allowed_ips="0.0.0.0/0"
uci add_list network.wgserver.allowed_ips="::/0"
uci commit network
service network restart

Resolve race conditions and configure dynamic connection if necessary.

Testing

Establish the VPN connection. Verify your routing with traceroute and traceroute6. 

traceroute openwrt.org
traceroute6 openwrt.org

Check your IP and DNS provider.

On router:

  • Go to LuCI > Status > Wireguard and look for peer device connected with an IPv4 or IPv6 address and with a recent handshake time
  • Go to LuCI > Network > Diagnostics and ipv4 ping client device IP eg. 10.0.0.10

On client device depending on wireguard software:

  • Check transfer traffic for tx & rx
  • Ping router internal lan IP
  • Check public IP address in a browser – https://whatsmyip.com – should see public IP address of ISP for the router

Troubleshooting

Collect and analyze the following information. 

# Restart services
service log restart; service network restart; sleep 10
 
# Log and status
logread -e vpn; netstat -l -n -p | grep -e "^udp\s.*\s-$"
 
# Runtime configuration
pgrep -f -a wg; wg show; wg showconf wg0
ip address show; ip route show table all
ip rule show; ip -6 rule show; nft list ruleset
 
# Persistent configuration
uci show network; uci show firewall; crontab -l
  1. Check keys match
  2. Check the tunnel route
  3. Check your addresses (LuCI will not remind you to set a netmask!)
  4. Check your firewall

You can use the `netcat` package to make an arbitrary UDP connection to your endpoint, and `tcpdump udp port ENDPOINT_PORT` at your other end if it is a Linux machine to see the result. 

echo hello | netcat -u ENDPOINT_HOST ENDPOINT_PORT